Relay services provide deaf and hearing impaired people the ability to make phone calls. A deaf customer types what they wish to say to the person they are calling (also referred to as the recipient or the far party), and the relay communications assistant (CA) voices the text to the hearing party being called. When the hearing party speaks, the CA types what they say for transmission to a screen for the deaf caller to read.
Many deaf or hearing impaired users can speak and want the ability to talk instead of type for their outgoing part of the conversation. The only part of relay they require or desire is the translation of the other party's voice into text that they can read. This ‘one-way’ relay is known as voice carry over (VCO).